disabling audio lineout ?

ok here is the story : the tip of my headphones broke while connected to the macbook, my computer has this tip inside the audio plug and plays sounds on the useless lineout. There is no way to remove that thing (i tried everything, including matches with a bit of superglue !).

The only solution I see to get the sound back to the internal speakers is to disable the lineout, can someone please tell me how to do that ?

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